/Engine/Source/Runtime/Online/WebSockets/Public/IWebSocket.h
Delegate called when any web socket data has been received. May be called multiple times for a message if the message was split into multiple frames. This is called for every web socket fragment. BytesRemaining is the number of bytes left in the current fragment.
class FWebSocketRawMessageEvent : public TBaseMulticastDelegate_ThreeParams< void, const void *, SIZE_T, SIZE_T >